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Re: Hibernate get fields

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On Wednesday, August 23, 2023 at 1:43:28 PM UTC-4, Daniele Futtorovic wrote:
> You can probably make the DTO an inner class, yeah. No new class file 
> that way. 
> 
> But really, is this something you should be worrying about? 
> 
> -- 
> DF.

The only way I've found to select 2 fields from a table that has more than 2 fields is to create a 2 field constructor, which doesn't work if you have 2 queries with the same number and type of fields but different fields, or create a static inner class which requires duplicating the field definitions and fully qualifying the class.

@Entity
@Table(name = "V_TABLE_DEF", schema = "MYSCHEMA")
@Getter
@Setter
public class MyDTO implements Serializable {
@Id
@Column(name = "FIELD_ONE")
private String fieldOne;
@Column(name = "FIELD_TWO")
private String fieldTwo;
public MyDTO(){}
public MyDTO(String f1, String f2) {setFieldOne(f1);setFieldTwo(f2);}
@Getter
@Setter
public static class F1F2 {
public F1F2(String f1,String f2) {setFieldOne(f1);setFieldTwo(f2);}
@Id
@Column(name = "FIELD_ONE")
private String fieldOne;
@Column(name = "FIELD_TWO")
private String fieldTwo;
}
... // more fields
}

private static final String MY_QUERY = "SELECT new MyDTO(fieldOne, fieldTwo) FROM MyDTO";
private static final String MY_INNER_QUERY = "SELECT new org.mypackage.MyDTO$F1F2(fieldOne, fieldTwo) FROM MyDTO";
try (Session session = MyHibernateUtil.getSessionFactory().openSession();) {
Query<MyDTO> query = session.createQuery(MY_QUERY,MyDTO.class);
List<MyDTO> results = query.list();
Query<MyDTO.F1F2> innerQuery = session.createQuery(MY_INNER_QUERY,MyDTO.F1F2.class);
List<MyDTO.F1F2> innerResults = innerQuery.list();
}

If we want to be able to use the outer class, perhaps setting some other values and passing it back to a Hibernate update method, we can create a constructor for the outer class that accepts an instance of the inner class and convert the results after the fact (not in the Hibernate select).

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Hibernate get fields "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-08-23 07:15 -0700
  Re: Hibernate get fields Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2023-08-23 19:43 +0200
    Re: Hibernate get fields "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-08-24 06:11 -0700
  Re: Hibernate get fields Arne Vajhøj <arne@vajhoej.dk> - 2023-08-25 19:58 -0400

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